Alarm clocks are known to produce wake-up alarm signals at a predetermined time. In most cases the alarm signals are acoustic signals loud enough to be perceived by a sleeping human being. It is noted that other kinds of alarm signals can be used like, for example, optical signals. The intensity of the alarm signal should be high enough to wake up any sleeping person reliably. However, it is also desired to wake up the person gently to avoid a sudden rush from sleep to high body activity, as such a swift change of body functions is often found to be annoying and has proven to be unhealthy. There are several medical reasons to avoid such an extreme change of body activity level. Just to give one example, there is a certain risk of harming the heart functions. Instead it is desired to wake up gradually in a gentle way so that the human body can increase its activity level in smaller steps.
One way to make a person wake up gradually is to produce a sequence of alarm signals of moderate intensity like, for example, acoustic alarm signal which are separated by timeouts. Each alarm signal can be turned off or suppressed. A few minutes after one alarm signal has been turned off, another alarm signal is produced so that the person to be waked up has to make another move to turn off the alarm clock, and the next alarm signal of the sequence will begin after another timeout. This method for controlling a wake-up alarm is known as “snoozing”, as it gives the possibility to wake up a person gradually after a number of alarm signals within the sequence. However, experience has shown that in cases when the person is very tired, he or she will hit the “snooze” button to turn off the alarm signal again and again without making any progress to wake up completely. Therefore this well-known “snooze function” does not satisfactorily solve the problem of waking up a person gently and gradually until the person is fully awake.
Another approach to wake up a person is to produce alarm signals which promote a physical effort to turn off the alarm. For example an alarm is produced which can only be turned off by leaving the bed immediately to hit a snooze button which is arranged at a location remote from the bed, or which is provided at an object moving through the bedroom and that has to be caught before it can be turned off. Although alarm clocks of this kind provide a reliable wake-up function, as some physical effort is needed to turn off the alarm, they share the same disadvantage as many other alarm clocks as mentioned above, namely to increase the body activity level not gradually but within a very short time span.
It is therefore an object of the present invention to provide an alarm clock which gradually increases the physical effort needed to turn off the alarm. Another object of the present invention lies in the provision of a corresponding method for controlling a wake-up alarm.